Possible causes for the dipole pattern of spring forest fires between Indo-China Peninsula and Northeast Asia

Recent extreme wildfire events have significantly increased, garnering widespread attention. Wildfires occurring simultaneously in multiple regions can result in more severe impacts than isolated events. Here, we examine the spatiotemporal characteristics of spring forest fires over East Asia and identify the regions over the Indo-China Peninsula (ICP) and Northeast Asia (NEA) that have contrasting changes in forest fires during 2003–2020. Our results show a robust dipole pattern in spring forest fires between the two regions, characterized by out-of-phase fire metrics (i.e., fire occurrences, burned areas). We also analyze the Fire Weather Index, vapor pressure deficit, total precipitation, and soil moisture, all of which exhibit opposite variations between ICP and NEA. Furthermore, the dipole pattern is linked to a meridional dipole structure in mid-tropospheric circulation anomalies over the Western Pacific–NEA regions. During the positive dipole phases (i.e., enhanced forest fire activity in ICP, but reduced in NEA), ICP exhibits higher temperature, lower humidity, reduced total cloud cover, and moisture flux divergence accompanied by subsidence, collectively promoting fire risk. In contrast, NEA experiences opposite atmospheric conditions that suppress fire activity. Our results highlight the critical role of large-scale atmospheric circulation in shaping regional fire variability, and facilitate the wildfire risk prediction under climate change.